Method for producing an exhaust gas cleaning metal carrier

ABSTRACT

A metal carrier and a production method thereof for carrying an exhaust gas cleaning catalyst for automobiles, autobicycles, and industrial equipment. The metal carrier includes a metal honeycomb core body pressed into a metal outer cylinder, and the joined portion of the a flat plate and a corrugated plate forming the metal honeycomb core body includes a solder material coated in spots or stripes at peaks of corrugation of the corrugated plate. The solder material in the joined portion of the flat plate and the corrugated plate has a thickness of less than 100 μm, the positions of the joined portions are different between the surface and backside of the flat plate and corrugated plate, and the joined portions are present through an unjoined area having a length of more than 5% of the length of the metal honeycomb core body from an end face of the metal honeycomb core body at the exhaust gas inlet side.

This application is based on International Application No.PCT/JP94/00919, filed Jun. 7, 1994.

TECHNICAL FIELD

This invention relates to a metal carrier for carrying an exhaust gascleaning catalyst for automobiles, autobicycles, and industrialequipment, and a production method thereof.

BACKGROUND TECHNOLOGY

As a catalyst carrier for cleaning exhaust gas of automobiles, ahoneycomb-formed metal carrier comprising heat-resistant stainless steelis known. The metal carrier is formed by winding round a stack of a flatplate and a corrugated plate to form a honeycomb core body and joiningthe outer periphery of the honeycomb core body and inner surface of ametal outer cylinder.

Various methods are known as the production method of the metal carrier.For example, Japanese Patent Publication 63-44466 describes a metalcarrier in which a pile of a flat plate and a corrugated plate is woundround, and the vicinity at least one of end faces of the wound honeycombcore body is soldered. However, such a metal carrier, when actually usedon an internal combustion engine for automobile, tends to undergodeformation of the honeycomb core body or breakage of a foil on an outerperiphery of the honeycomb core body due to thermal fatigue by heatcycle of heating and cooling. In particular, the exhaust gas inlet sideof the honeycomb core body undergoes considerable cell deformation andfoil breakage because it is exposed to high-temperature exhaust gas.Further, the metal carrier may be broken at the joined portion due toengine vibration and vibration during traveling.

Further, Japanese Patent Laid-open Publication 56-4373 discloses ahoneycomb core body produced by a method in which solder is coated on aflat steel plate or at peaks of a corrugated steel plate through asupply roller from a vessel filled with liquid solder paste, and theformer is wound round with a corrugated steel plate, or the latter iswound round with a flat steel plate. The patent also discloses ahoneycomb core body produced by a method in which before coating solder,an adhesive is coated at a position to be solder coated through a supplydevice, and wound round while sprinkling a powder-formed solder materialby a distribution device. In these honeycomb core bodies, thepowder-formed solder material is piled in layers between the flat steelplate and the corrugated steel plate. Further, since the stack of thepowder-formed solder material particles between the flat steel plate andthe corrugated steel plate exists in amounts of twice the number ofturns from the center of the honeycomb core body to the outermostperiphery, when treated by vacuum soldering, the solder material meltsto generate voids between the flat steel plate and the corrugated steelplate, and the voids in layers collect at several positions. Therefore,the honeycomb core body obtained by this method has unsoldered portionsbetween the flat steel plate and the corrugated steel plate. Further,since the solder thickness increases at the joined portion of the flatsteel plate and the corrugated plate, the core body tends to break atthe brittle solder material and is insufficient in strength.

As another method, Japanese Patent Laid-open Publication 4-141238discloses a production method of a metal carrier, in which a pluralityof binder injectors having needles on the surface and backside of acorrugated foil are disposed in a single or multiple stages parallel tothe corrugation, and operation of the binder injectors is selected sothat the binder is coated at peaks of the corrugation in a previouslydesigned range according to the movement of the corrugated foil toselect joining positions of the corrugated foil and flat foil at desiredpositions of the honeycomb core body.

In producing a honeycomb core body by this method, to select a joiningposition of the corrugated foil and flat foil at a desired position ofthe honeycomb core body, first only the binder is supplied, afterwinding the honeycomb core body, or after containing it in an outercylinder, a process to sprinkle the solder material from the end face ofthe honeycomb core body to apply the solder material to the bindercoating portion. This results in an increase in cost. Further, when thebinder is roll coated on the corrugated plate or the flat plate beforeforming the honeycomb core body and the solder material is alsosupplied, wound round into the honeycomb core body, and then solderingis made, since the solder material is sandwiched between the flat plateand corrugated plate, the solder material melts by soldering treatmentto generate voids between both plates, and effective joining is notobtained. This is also true for a slurry which is a mixture of thebinder and powder-formed solder. Since the binder and powder-formedsolder are sandwiched between the flat plate and corrugated plate, thesolder material melts after soldering to generate voids between bothplates, and cannot provide effective joining. When the slurry is coatedon the same joining position of the surface and backside of the flatplate and corrugated plate, voids further increase between both platesdue to melting of the solder material from the slurry sandwiched betweenthe flat plate and corrugated plate, resulting in insufficient joining.Further, Ni, Cr, and Si, which are ingredients of the solder material,diffuse into the base material, and formation of an intermetalliccompound concentrates in a same position, degrading the strength.

Then, there have heretofore been known various types of exhaust gascleaning apparatus, in which a metal honeycomb body is inserted into ametal outer cylinder, and a gas cleaning catalyst is carried on themetal honeycomb body. In particular, various types of honeycombstructures have been proposed to control or prevent peeling or damage ofthe joined portion due to a strain caused by a thermal stress generatedby heat of exhaust gas of automobiles. For example, Japanese PatentLaid-open Publication 4-29750 discloses a metal carrier in which a metalhoneycomb core body and an outer cylinder are joined with a plurality ofbands formed at 1-15 mm ring-formed intervals in an axial direction ofthe metal carrier. This absorbs a stress generated in the axialdirection of the carrier during cooling/heating cycle by deforming anunjoined portion at the ring-formed spacing to disperse a stress actingon the joined portion and unjoined portion. However, in some cases,depending on the joining condition of the metal honeycomb core body, thestress cannot be efficiently dispersed even by joining the plurality ofbands between the outer cylinder and the metal honeycomb core body. Forexample, when the boundary of the metal honeycomb core body and theouter cylinder is in line with the boundary in the metal honeycomb corebody, the stress is concentrated at that position due to the heat cycle,and the foil is broken from that position. Further, Japanese PatentLaid-open Publication 4-148016 discloses a metal carrier which has aregion where a flat foil and a corrugated foil are joined in an axialdirection in a length of 5 to 20% the axial direction length of themetal honeycomb core body. An outer layer reinforcing layer is joined inan axial direction within five layers from the outer most layer towardsthe inside, and the metal outer cylinder and the metal honeycomb corebody are joined in a region in the axial direction within the outerlayer reinforcing layer. In this case, the metal outer cylinder and themetal honeycomb core body are joined at a position in the axialdirection to relax the thermal deformation in the axial direction of themetal outer cylinder and the metal honeycomb core body. However, becausethe metal outer cylinder and the metal honeycomb core body are joinedonly at a position, mechanical vibrations of the engine or vibrations ofthe vehicle during traveling tend to concentrate in the joined portion,leading to a breakage.

Further, Japanese Utility Model Laid-open Publication 2-83320 describesan exhaust gas cleaning apparatus comprising a plurality of metalhoneycomb core bodies having a number of reticulated ventilation holesin an axial direction formed by stacking thin flat band materials andcorrugated band materials to contact each other, mounted at intervals ina metal case with both ends open. Thus, an exhaust gas cleaningapparatus in which at least one position is joined is disclosed, exceptfor a case that a contact surface of the outer peripheral surfaces ofthe individual metal honeycomb core bodies and the inner wall surface ofthe metal case are simultaneously joined with the inner wall surface ofthe metal case in the vicinity of both ends of the metal honeycomb corebody. Japanese Utility Model Laid-open Publication 2-85814 describes anexhaust gas cleaning apparatus which comprises two metal honeycomb corebodies having a number of reticulated ventilation holes in the axialdirection, manufactured by stacking thin metal flat band materials andcorrugated band materials to contact each other, mounted with spacing ina cylindrical metal outer cylinder having both ends open and an enlargeddiameter section, wherein the outer peripheral surface in the vicinityof the opening of the metal outer cylinder of each metal honeycomb corebody is mounted to the inner wall surface of the metal outer cylinder,and the outer peripheral surface in the vicinity of the spacing of theindividual metal honeycomb core bodies does not contact the inner wallsurface of the metal outer cylinder.

In these exhaust gas cleaning apparatus, a plurality of metal honeycombcore bodies are disposed at spaces in a metal outer cylinder, and only aportion in the axial direction of the contact surface of the outerperipheral surface of the individual metal honeycomb core body and theinner wall surface of the metal outer cylinder is annularly joined,preferably over the entire periphery to disperse and relax thermalstress, thereby preventing peeling of the outer peripheral surface ofthe metal honeycomb core body and the inner wall surface of the metalouter cylinder or peeling or cracking of the flat plates and thecorrugated plates forming the metal honeycomb core bodies due to thermalstress and thermal deformation.

However, even when thermal stress is dispersed and relaxed by the abovemethod, it is impossible to absorb a strain in the vicinity of the outerperipheral surface of the metal honeycomb core body due to thermalstress and thermal deformation generated in the exhaust gas cleaningapparatus. Therefore, the vicinity of the peripheral surface is liableto be subjected to thermal stress and thermal deformation, resulting incell deformation or peeling of the flat plate and corrugated plate.Further, joining the inner wall surface of the metal outer cylinder andthe outer peripheral surface of the metal honeycomb core body at only aportion tends to weaken the joining, and cannot withstand the pressureof exhaust gas flow at high temperatures.

Further, in a conventional metal carrier, a plurality of metal honeycombcore bodies are joined at spaces in a metal outer cylinder (e.g.Japanese Utility Model Laid-open Publication 2-83320). In this carrier,in an attempt to remove thermal stress and thermal deformation generatedin the metal carrier at high temperatures by only joining of the outerperipheral surface of the metal honeycomb core body and the inner wallsurface of the metal outer cylinder, a strain occurs that cannot beremoved, and the metal honeycomb core body may be broken by the strainif the metal honeycomb core bodies are not joined at spaces. This easilyleads to a large-sized exhaust gas cleaning apparatus, except for a caseto intentionally generate a turbulent flow. Further, as described inJapanese Utility Model Laid-open Publication 2-85815, a large-diametersection provided in the metal outer cylinder leads to a large-sizedexhaust gas cleaning apparatus.

On the other hand, in an exhaust gas cleaning apparatus carrying a gascleaning catalyst on a metal honeycomb core body, it has been known touse a curved metal carrier. For example, Japanese Utility ModelLaid-open Publication 4-78938 proposes a curved metal carrier, in whichflat plates and corrugated plates are stacked in alternation to form ahoneycomb structure, and the honeycomb structure is inserted into anouter cylinder. In the metal carrier, arrays of slits is provided sothat each slit has a length of more than one wave in the cross directionof the flat plates and corrugated plates, the slits are arranged atspaces in the longitudinal direction, and a number of the arrays areformed in parallel and shifted from each other.

However, in the curved metal carrier, since the flat plates andcorrugated plates forming the metal honeycomb core body are providedwith slits and inserted into a curved metal outer cylinder, if thermalstress and thermal deformation occur in the metal carrier at hightemperatures, the slits expand to generate cracking, cell deformation,peeling of joined portions, and breakage of the metal honeycomb corebody. Further, since the flat plates and corrugated plates have slits,when the metal honeycomb core body is inserted into the curved metalouter cylinder after the carrier is formed, the honeycomb structurecannot be maintained, and the predetermined cell structure cannot bemaintained. That is, when designing a metal carrier, it is difficult toensure the desired porosity ratio and surface area. Further, due to theslits, exhaust gas tends to flow only the vicinity of the outerperipheral surface of the curved metal outer cylinder, resulting in aconsiderably deteriorated efficiency of exhaust gas cleaning.

Then, the inventors have conducted intensive studies to solve suchdefects and found that flat plates and corrugated plates are solderedwith a solder material coated in spots or stripes on the peaks of thecorrugated plate to form a metal honeycomb core body, while the soldermaterial coated on the metal honeycomb core body still has a fluidityand the solder material coated on the inner wall surface of the metalouter cylinder has no fluidity, the outer peripheral surface of themetal honeycomb core body and the inner wall surface of the metal outercylinder are assembled, and then soldering heat treated, therebysufficiently absorbing a thermal stress and achieving the presentinvention. Therefore, a primary object of the present invention is toprovide a stable metal carrier which sufficiently absorbs a thermalstress and, when used on vehicles, can withstand practical use for anextended period of time.

DISCLOSURE OF THE INVENTION

In accordance with the present invention, there is provided an exhaustgas cleaning metal carrier composed of one or more metal honeycomb corebodies formed by joining a flat plate and a corrugated plate, andpressed into a metal outer cylinder, characterized in that the joinedportion of the flat plate and the corrugated plate comprises a pluralityof joining spots or stripes of a solder material coated at peaks of thecorrugated plate, the solder material of the joined portion of the flatplate and the corrugated plate has a thickness of 100 μm or less, andthe positions of the joined portions of the flat plate and thecorrugated plate are offset between the front surface and the backsideof the corrugated plate. There is in the honeycomb core an unjoinedportion, i.e., solder-free portion, of a length of 5% or more of thelength of the honeycomb core body from the metal honeycomb end face atthe exhaust gas inlet side. Further, the metal honeycomb core body andthe metal outer cylinder are joined with a solder material coated instripes on the inner wall of the metal outer cylinder. The joinedportion of the core body at the outermost periphery of the metalhoneycomb core body is not in line with (i.e., is offset from) thejoined portion of the core body with the metal outer cylinder, and themetal honeycomb core body is joined intermittently in the axial andperipheral directions. The metal outer cylinder is not limited to acircular form, but may be curved with a desired curvature.

There is further provided according to the present invention a methodfor producing a metal carrier matrix, characterized in that a pluralityof slurry supplying devices having a nozzle are disposed in multiplestages parallel to the direction of corrugation of a corrugated plate, aslurry comprising a powder-formed solder material and a binder is coatedby the slurry supplying devices at peaks of corrugation according tomovement of the corrugated plate and at predetermined positions, thecorrugated plate and a flat plate are stacked and wound round to form ametal honeycomb core body, a slurry comprising the powder-formed soldermaterial and a binder is coated on an inner wall surface of a metalouter cylinder, then the metal honeycomb core body is pressed into themetal outer cylinder, and both parts are joined by vacuum soldering toobtain an exhaust gas cleaning metal carrier.

In the above production method, it is preferable that the slurrycontaining the powder-formed solder and the binder is coated by theslurry supplying devices, and then the slurry coated at peaks of thecorrugation is spread by a brush or roll in longitudinal and crossdirections of the corrugated plate to uniformalize the coatingthickness.

By the above method, a metal honeycomb core body matrix can be obtained,in which the joined portions of the flat plate and the corrugated plateare present through unjoined portions having a length of more than 5% ofthe length of the metal honeycomb core body, and a plurality of joinedbands perpendicular to the axial direction are present on one and thesame surface of the metal honeycomb core body.

There is further provided according to the present invention a methodfor producing a metal carrier comprising a plurality of metal honeycombcore bodies pressed into a metal outer cylinder parallel to the axialdirection, characterized in that peaks of the corrugated plate arecoated with a slurry-formed solder material in spots or stripes, and aflat plate and the corrugated plate are stacked and wound round to forma metal honeycomb core body. On the other hand, an inner wall surface ofthe metal outer cylinder is coated with a solder material, while theslurry-formed solder material coated at peaks of the corrugated plateand the solder material coated on the inner wall surface of the metalouter cylinder has no fluidity, the metal honeycomb core body is pressedinto the metal outer cylinder, the outer cylinder is curved asnecessary, dried and soldering heat treated to join the metal honeycombcore body and the metal outer cylinder.

As another production method, which is particularly useful when themetal outer cylinder is curved, is now described. In this case aplurality of metal honeycomb core bodies formed by joining a flat plateand a corrugated plate are pressed into the curved metal outer cylinderparallel to the axial direction. Here too, peaks of the corrugated plateare coated with a slurry-formed solder material in spots or stripes, theflat plate and the corrugated plate are stacked and wound round to forma metal honeycomb core body. According to this embodiment, a soldermaterial is coated on an inner wall surface, while the slurry-formedsolder material coated at peaks of the corrugated plate has a fluidityand the solder material coated on the inner wall surface of the metalouter cylinder has no fluidity, the metal honeycomb core bodies arepressed into the metal outer cylinder, the metal outer cylinder iscurved with a desired curvature, dried and soldering heat treated tojoin the metal honeycomb core bodies and the metal outer cylinder in thecurved condition.

The present invention will now be described in detail. When the metalcarrier is installed on an actual vehicle, it is subjected tocooling/heating cycles, and a temperature gradient occurs in the axialand radial directions.

Further, since most present metal carriers use, in the metal honeycombcore body, a ferrite type stainless steel containing a highconcentration of Al, which is highly resistant to oxidation, thefollowing stresses are applied between the metal honeycomb core bodiesand between the metal honeycomb core body and the outer cylinder due toa difference in thermal expansion coefficient between the metalhoneycomb core body and the metal outer cylinder and the temperaturegradient occurring in the metal carrier.

In the radial direction of the honeycomb, the metal honeycomb core bodyis pressed against the outer cylinder due to thermal expansion of themetal honeycomb core body during heating (temperature of the metalhoneycomb core body>temperature of the metal outer cylinder, thermalexpansion coefficient of the metal honeycomb core body>thermal expansioncoefficient of the metal outer cylinder), and a deformation occurs inthe cell of the metal honeycomb core body. In particular, when the endsurface of the metal honeycomb core body is bound by soldering, thermalstress due to thermal expansion cannot be relaxed, which causes bucklingof the flat plate forming the metal honeycomb core body, and the celldeformation of the metal honeycomb core body is further increased.Further, the exhaust gas inlet side of the metal honeycomb core body isexposed to high-temperature exhaust gas compared to the outlet side, andthe temperature is considered to be higher than 1,000° C. by a reactionbetween the exhaust gas and the catalyst. Therefore, cell deformation ofthe metal honeycomb core body is particularly considerable at theexhaust gas inlet side.

As described above, due to the cell deformation, the metal honeycombcore decreases in the core diameter, and a tensile force occurs betweenthe metal outer cylinder and the metal honeycomb core body, resulting ina breakage in the foil of the outer periphery. To prevent this, thevicinity of the end surface at the exhaust gas inlet side, which is themost considerable in cell deformation, should not be bound. Further, torelax thermal stress in the axial and radial directions of the metalhoneycomb core body, the metal honeycomb core body is joined in spots ora plurality of stripes in the axial direction.

Further, when joined portions of the metal honeycomb core bodies are inline with those of the metal outer cylinder and the metal honeycomb corebody, those portions tend to be applied with a tensile stress to causebreakage in the outermost periphery of the metal honeycomb core body. Toprevent this, joined portions of the outermost periphery of thehoneycomb core body should not be in line with those of the metal outercylinder to once separate the metal honeycomb core body from the metalouter cylinder.

On the other hand, in the axial direction, since the metal honeycombcore body is higher in temperature than the metal outer cylinder, themetal honeycomb core body tends to expand in the axial direction of themetal honeycomb core body more than the metal outer cylinder. Therefore,if the metal honeycomb core body and the metal outer cylinder are joinedin two positions, a shearing stress applies to the joined portions.Further, the longer the joining intervals, the greater the expansion,the shearing stress applied to the joined portions becomes higher,resulting in breakage in the joined portions. To prevent this, the metalhoneycomb core body is joined at one position in the axial direction,thereby relaxing thermal stress in the axial direction of the metalhoneycomb core body. However, by joining at a single position,vibrations of the engine or during traveling tend to concentrate in oneposition, resulting in breakage at the joined portion. Therefore,intermittent joining at a plurality of positions is preferable in viewof the joining strength and relaxation of thermal stress in the axialand radial directions.

The reason why the unjoined portion between the core body and the metalouter cylinder is more than 5% of the length of the metal honeycomb corebody is that, as a result of heat cycle tests of the metal honeycombcore body bound at the end by soldering, considerable cell deformationis noted in a length less than about 5% of the length of the metalhoneycomb core body.

Further, by joining with a plurality of joining bands perpendicular tothe axial direction on the same surface of the metal honeycomb corebody, strain generated in the axial direction is dispersed to reduce thestrain acting on the boundary of the joined portion and unjoinedportion.

In the present invention, the solder material of the joined portion ofthe flat plate and the corrugated plate has a thickness of 100 μm orless. In a test where the outer peripheral metal cylinder of the metalhoneycomb core body is held, and the metal honeycomb core body ispressed by a punching rod to draw out the metal honeycomb core body, therelationship between the punching strength and the solder materialthickness as shown in FIG. 1 is obtained. As a result, the punchingstrength is considerably reduced when the solder material thicknessexceeds 100 μm. This is considered as due to the fact that breakageoccurs in the base material at the solder material thickness of 100 μmor less, and breakage occurs in the solder material, which is brittlecompared to the base material, when the solder material thickness ismore than 100 μm. Therefore, the solder material of the joined portionof the flat plate and the corrugated plate is required to have athickness of 100 μm or less.

Further, it has been known that when the flat plate and the corrugatedplate are joined by soldering, Ni, Cr or Si as ingredients of the soldermaterial diffuse into the base material to form an intermetalliccompound. Therefore, when the soldered portions of the flat plate or thecorrugated plate are juxtapose between the surface and the backside,formation of the intermetallic compound concentrates in the juxtaposedposition, resulting in a reduction of strength. Therefore, the joinedportions of the flat plate or the corrugated plate must be different(offset) between the surface and the backside.

In view of spreading of the solder material, the slurry coatingpositions on the surface and the backside of the corrugated plate arepreferred to be apart from each other by 4 mm or more.

To produce a metal carrier which is superior in durability to extremeheat cycles and strong mechanical vibrations, the solder material mustbe supplied in spots or a plurality of stripes at a desired positionapart by more than 5% of the length of the metal honeycomb core bodyfrom the end surface at the exhaust gas inlet side.

When soldering in stripes, soldering is easily achieved by supplying anamorphous foil solder to the desired positions other than the endsurface. However, since the amorphous foil solder contains boron as aningredient, when soldering, the boron tends to diffuse into the basematerial, reducing the heat resistance of the foil. Therefore, it is notpreferable to use an amorphous foil solder containing boron.

Then, the present invention uses a powdered solder material which doesnot contain boron as an ingredient, which is mixed with a binder to forma slurry, supplied in stripes to a desired position at peaks of thecorrugated plate, and a flat plate and the solder-coated corrugatedplate are stacked and wound round to form a metal honeycomb core body.

Boron has an effect to improve wetting of the solder material, however,it is not preferable because it degrades the heat resistance and, in thepresent invention, the soldered portion tends to spread too much,resulting in overlapping of the joined portions of the flat plate andcorrugated plate on the surface and backside.

Then, the structure of the metal carrier of the present invention willbe described in detail.

The metal carrier according to the present invention, which has theabove-described structure, may have any cross sectional shape, such ascylindrical, race track (i.e., and), or other form. The plurality ofmetal honeycomb core bodies pressed into the metal outer cylinder maycontact each other, or may be apart from each other.

Production method of the metal carrier according to the presentinvention will be described.

First, a slurry containing a powdered solder material and a binder iscoated by a nozzle or the like in spots or stripes at peaks of thecorrugated plate, and the corrugated plate and a flat plate are stackedand wound round to form a metal honeycomb core body. This formationmethod is not specifically limited, but it is important to supply thesolder material in spots or stripes at peaks of the corrugated plate.The thus formed metal honeycomb core body is pressed into the metalouter cylinder to join them. In the joining of the metal honeycomb corebody and the metal outer cylinder, the metal honeycomb core body ispressed into the metal outer cylinder while the solder material coatedon the metal honeycomb core body maintains a fluidity and the soldermaterial coated on the inner wall surface of the metal outer cylinderhas no fluidity. Since the metal honeycomb core body is pressed into themetal outer cylinder while the solder material maintains a fluidity, andthe joining portions having the solder material between the flat plateand the corrugated plate are not yet joined, they can freely move theirpositions, and can thus maintain a condition of least strain. Since thesolder material coated on the inner wall surface of the metal outercylinder has no fluidity, the solder material does not flow when themetal honeycomb core body is pressed in, and can be joined at apredetermined position.

The individual metal honeycomb core bodies can be joined so that theyare apart from each other when exhaust gas flow is intentionally madeturbulent, or not apart from each other for otherwise. This enables acompact exhaust gas cleaning apparatus by the metal honeycomb corebodies disposed not apart from each other, except for a case where aturbulent flow is intentionally generated.

In the production method of a curved metal honeycomb carrier, after aplurality of uncurved metal honeycomb core bodies are pressed into themetal outer cylinder before soldering heat treatment, the result iscurved with a desired curvature, or after a plurality of metal honeycombcore bodies are pressed into a metal outer cylinder which is previouslycurved with a desired curvature, and the result is soldering heattreated, thereby easily forming a curved metal carrier, which is highlyresistant to thermal stress and thermal deformation at hightemperatures.

An apparatus for coating a slurry, which is a mixture of a powderedsolder material and a binder for joining the metal honeycomb core bodyformed by stacking and winding round a flat plate and a corrugatedplate, at desired positions on the inner surface of the metal outercylinder preferably comprises a metal outer cylinder carrying-in device,a metal outer cylinder rotating and supporting device, a solder materialcoating device for coating the solder material on the inner surface ofthe metal outer cylinder, a metal outer cylinder carrying-out andrecovery device after solder material coating, and means for rotatingthe metal outer cylinder rotating and supporting device and operatingthe solder material coating apparatus when the metal outer cylinder iscarried in by the metal outer cylinder carrying-in device.

That is, the coating apparatus has a solder material supply device forsupplying the slurry as a mixture of the powdered solder material andthe binder, a mechanism for evenly coating the solder material at adesired position of the inner surface of the metal outer cylinder, and amechanism for rotating and supporting the metal outer cylinder andcarrying the metal outer cylinder. The means for rotating the metalouter cylinder rotating and supporting device and operating the soldermaterial coating apparatus when the metal outer cylinder is carried inby the metal outer cylinder carrying-in device which can be controlled,for example, by a sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the relationship between the solder materialthickness and the punching strength of the joined portion of a flatplate and a corrugated plate of a metal honeycomb core body;

FIG. 2 is a schematic perspective view of a metal honeycomb carrier;

FIG. 3 is a schematic perspective cross sectional view of a metalcarrier;

FIG. 4 is a schematic enlarged cross sectional view showing part of ajoined portion of an inner wall surface of an outer cylinder and themetal carrier; and

FIG. 5 is a schematic cross sectional view when two metal honeycomb corebodies apart from each other are pressed into a metal outer cylinder.

FIG. 6 is a schematic view for explaining the production method of themetal honeycomb core body of the present invention;

FIG. 7 is a schematic view showing a process from solder materialsupplying to the metal outer cylinder to vacuum soldering;

FIG. 8 is a schematic cross sectional plan view showing the curved metalcarrier according to the present invention;

FIG. 9 is a schematic view showing the production method of the curvedmetal carrier of the present invention; and

FIG. 10 is a schematic front view of a coating apparatus of the presentinvention.

FIG. 11 is a schematic cross sectional view showing soldering conditionof the metal carrier of Example 1 of the present invention;

FIG. 12 is a schematic cross sectional perspective view showingsoldering condition of the metal carrier of Example 2 of the presentinvention;

FIG. 13 is a schematic cross sectional perspective view showingsoldering condition of the metal carrier of Comparative Example 1;

FIG. 14 is a schematic cross sectional perspective view showingsoldering condition of the metal carrier of Comparative Example 2;

FIG. 15 is a schematic cross sectional perspective view showingsoldering condition of the metal carrier of Comparative Example 3;

FIG. 16 is a schematic cross sectional perspective view showingsoldering condition of the metal carrier of Example 3 of the presentinvention.

FIG. 17 is a schematic cross sectional perspective view showingsoldering condition of the metal carrier of Example 4 of the presentinvention;

FIG. 18 and FIG. 19 are individually schematic cross sectionalperspective views showing soldering condition of the metal carriers ofComparative Examples 4 and 5 of the present invention.

Then, the metal carrier of the present invention will be described withreference to the drawings, however, it is needless to say that thepresent invention is not limited to those shown in the drawings.

FIG. 2 is a schematic perspective view showing the metal carrier of thepresent invention, FIG. 3 is a schematic cross sectional perspectiveview of FIG. 2, and FIG. 4 is a schematic enlarged view showing joiningof the inner wall surface of the metal outer cylinder and the metalhoneycomb core body.

Referring to FIG. 2, a metal carrier 1 comprises a metal honeycomb corebody 3 pressed in a metal outer cylinder 2. As shown in FIG. 4, theoutermost periphery of the metal honeycomb core body 3 and the innerwall surface of the metal outer cylinder are soldered, the solderingbeing achieved by a solder material 4 in a plurality of stripes. Themetal honeycomb core body 3 is formed by soldering a flat plate 31 and acorrugated plate 32. The soldering of the flat plate and the corrugatedplate is achieved by a solder material 41, 42, . . . coated in spots orstripes at peaks on the outer surface and inside surface, respectively,of the corrugated plate. The reference numeral 41, therefore, indicatesa portion joined with the solder material between the flat plate and thecorrugated plate and on the outside surface of the corrugated plate, and42 indicates a portion joined with the solder material between the flatplate and the corrugated plate and on the inside surface of thecorrugated plate. It is preferable that the positions of 41 and 42 areshifted from each other to reduce effects of the solder material on thebase material (FIG. 4). Furthermore, although not clearly shown in FIG.3 and FIG. 4, the stripes of solder material 4 should not be in linewith (i.e., should be offset or displaced with respect to) soldermaterial 41 at the outer periphery of the core body 3.

FIG. 5 is a schematic cross sectional perspective view showing a casewhen a separation part 9 is provided between two metal honeycomb bodies.

Then, the production method of the metal honeycomb core body of thepresent invention will be described with reference to the drawings.

FIG. 6 is a schematic view for explaining the solder material coatingmethod and the production method of the metal honeycomb core body of thepresent invention.

A slurry 14 produced by mixing a powdered solder material, free ofboron, and a binder is charged in a reservoir tank 16. The reservoirtank 16 is provided with a slurry supply tube 17, and a tip thereof hasa nozzle 13. The slurry 14 is fed through the slurry supply tube 17 tothe nozzle 13. The reservoir tank 16 is disposed at a position of thesame height as or lower than a corrugation peak 15 to be coated. Thenumber of the reservoir tanks 16 may be the same as the number of thenozzles 13 or one. When a single reservoir tank 16 is used, the slurrysupply tubes 17 of the same number of the nozzles 13 are attached to thereservoir tank 16, and the slurry 14 is branched by the slurry supplytubes to the individual nozzles 13.

By the use of the reservoir tank 16 and the slurry supply tube 17 to thenozzle 13, the slurry 14 can be supplied from the nozzle 13 to thecorrugation peak 15 stably for an extended time, without requiring aspace.

The nozzle 13 uses a flexible material, and is set between thecorrugation peak 15 and a corrugation valley 18. The supplied slurry 14is scraped by the corrugation peak 15 and coated thereon. Amount of theslurry 14 coated on the corrugation peak 15 is controlled only byadjusting the pressure of the reservoir tank 16 by a controller 6,without requiring a complex control.

The slurry 14 coated on the corrugation peak 15 is in a condition inwhich solder material particles are stacked in layers. When the flatplate and the corrugated plate are wound round in this condition to forma metal honeycomb core body and soldered, voids may be generated betweenthe corrugated plate and the flat plate. Further, the solder materialbetween the corrugated plate and the flat plate can have a thickness ofmore than 100 μm, with a considerably decreased punching strength. Inthe present invention, to uniformalize the coating thickness of thesolder material, the solder material is spread by a brush 5 or a roll inthe width direction and the longitudinal direction of the corrugationpeak, and the solder material-coated corrugated plate 32 and the flatplate 31 are stacked and wound round to form the metal honeycomb corebody 3, thereby preventing generation of voids and obtaining effectivejoined portions.

As the flat plate, for example, a heat-resistant steel of 20% Cr and 5%Al with a thickness of 0.05 mm and a width of 40 mm is used, and theflat plate is corrugated to be used as the corrugated plate.

As a method for joining the thus formed metal honeycomb core body 3 andthe inner wall surface of the metal outer cylinder 2, an amorphous foilsolder is wound round at a desired position on the outer periphery ofthe formed metal honeycomb core body 3, then the metal honeycomb corebody 3 is pressed into the metal outer cylinder 2, and vacuum soldered.However, with this method, as described above, since boron contained inthe amorphous foil solder diffuses into the base material of the metalhoneycomb core body, the heat resistance is deteriorated.

Therefore, in the present invention, the metal honeycomb core body 3 andthe inner wall surface of the metal outer cylinder 2 are joined by themethod shown in FIG. 7. Specifically, the slurry 14, obtained bypreviously mixing the powdered solder and a water-soluble or organicbinder, is coated by the nozzle 13 at a desired position on the innersurface of the metal outer cylinder 2 (step a), and placed in a dryingoven 7 to be dried (step b). Then. the metal honeycomb core body 3 ispressed using a pressing tool 10 into the metal outer cylinder (step c),and put in a vacuum soldering device 8 to be soldered (step d). In thisstep, if the metal honeycomb core body is pressed in without drying thesolder material, the stripe of solder material 4 tends to move with themetal honeycomb core body in the pressing direction, and the soldermaterial cannot be coated at the desired position. Therefore, it ispreferable to press the metal honeycomb core body into the metal outercylinder after drying the solder material. The vacuum soldering ispreferably made at 1,100° to 1,300° C. for more than 10 minutes undervacuum.

Then, the production method of a curved metal carrier will be describedin detail.

As shown in FIG. 6, a slurry-formed solder material is supplied to peakson the surface and backside of the corrugated plate, obtained bycorrugating a flat plate comprising a heat-resistant steel, and coatedin spots, or in stripes by a brush as necessary. Then, the corrugatedplate is stacked with a flat plate, and wound round to form a metalhoneycomb core body. A plurality of the resulting metal honeycomb corebodies, while the slurry-formed solder material maintains a fluidity andthe slurry-formed coated on the inner wall surface of the metal outercylinder has no fluidity, are disposed with or without spacing in themetal outer cylinder, dried, and subjected to soldering heat treatmentto simultaneously join the individual metal honeycomb core bodies, andthe metal honeycomb core body and the metal outer cylinder with thesolder material coated on the inner wall surface of the metal outercylinder.

The resulting metal honeycomb core body 3 is pressed into the metalouter cylinder 2 using the method shown in FIG. 7(c).

FIG. 8 is a schematic cross sectional view of the curved metal carrierof the present invention, and FIG. 9 explains the production method ofthe curved metal carrier. Referring to FIG. 9, after five units of themetal honeycomb core bodies 3 are pressed into the metal outer cylinder2 (a), for example, the carrier 1 is placed on a support 20, and pressedby a pressing die 19 from the upper side (b) to obtain a metal carrierhaving a desired curvature (c).

To enhance the precision, the carrier may be again pressed to be shaped.

Then, a solder material coating apparatus for coating the soldermaterial on the inner wall surface of the metal outer cylinder will bedescribed.

That is, the present invention is directed to a solder material coatingapparatus for coating the solder material on the inner surface of themetal outer cylinder comprising a solder material supplying device forsupplying a slurry, which is a mixture of a powdered solder and abinder, a mechanism for uniformly coating the solder material at adesired position on the inner surface of the metal outer cylinder, and amechanism for rotating and supporting the metal outer cylinder andcarrying the outer cylinder. As means for rotating a metal outercylinder rotating and supporting device when the metal outer cylinder iscarried in a predetermined position by a metal outer cylindercarrying-in device, and operating the solder material coating apparatus,a sensor, for example, may be used.

FIG. 10 is a schematic view of the solder material coating apparatus.Roughly divided, this apparatus comprises a metal outer cylindercarrying-in device, a metal outer cylinder rotating and supportingdevice, a solder material coating device for coating the solder materialon the inner surface of the metal outer cylinder, and a metal outercylinder carrying-out and recovery device for carrying out andrecovering the metal outer cylinder after solder material coating.

The metal outer cylinder carrying-in device and the metal outer cylinderrotating and supporting device will be described. The metal outercylinder carrying-in device and the metal outer cylinder rotating andsupporting device comprise a cylinder 24 for carrying in the metal outercylinder, a chuck 25 for rotating and supporting the metal outercylinder, a chuck drive motor 26 for rotating and supporting the metalouter cylinder, and a sensor 27. The metal outer cylinder is carriedfrom a metal outer cylinder delivery carrying-in guide 22 to a metalouter cylinder support carrying-in guide 23. Then the metal outercylinder is carried by a predetermined amount by the metal outercylinder carrying-in cylinder 24 in the direction of the metal outercylinder rotating and supporting chuck 25. After that, the cylinder 24returns to the original position, the metal outer cylinder 2 at themetal outer cylinder carrying-in guide 22 is set in the metal outercylinder carrying-in guide 23 by its own weight. The metal outercylinder 2 carried to the metal outer cylinder rotating and supportingchuck 25, when the sensor 27 detects that the cylinder 24 returns to theoriginal position, is clamped by the metal outer cylinder rotating andsupporting chuck 25. Then, the metal outer cylinder rotating andsupporting chuck 25 is automatically rotated by the motor 26.

Then, the solder material coating device for coating the solder materialon the inner surface of the metal outer cylinder will be described. Thesolder material coating device comprises a solder material supplycontroller 28, a slurry tank 29 for holding a slurry as a mixture of apowdered solder material and a binder, a nozzle 30 for injecting theslurry on the inner surface of the metal outer cylinder 2, a brush orroller 11 for uniformalizing the thickness of the slurry injected andspreading the slurry in the width direction, a movable table 33 formoving a holding tool 43 mounting the nozzle 30 and the brush or roller11 to the right and left, and an electromagnet 35 for vertically movinga sensor/stopper 34 for adjusting the moving length of the holding tool43. After the metal outer cylinder is clamped and rotated by the metalouter cylinder rotating and supporting chuck 25, the movable table 33moves to insert the holding tool 43 mounted to the movable table 33 intothe metal outer cylinder 2. The insertion length is controlled by thestopper 34. When the sensor/stopper 34 is contacted by the movable table33, the electromagnet 35 is energized to attract the holding tool 43. Asa result, the nozzle 30 and the brush or roller 11 mounted to the tip ofthe holding tool 43 are contacted with the inner surface of the metalouter cylinder 2. When the holding tool 43 is attracted by theelectromagnet 35, a detector 36 operates. As a result, the slurry is fedby the controller 28 from the slurry tank 29 through a tube 37, andinjected from the nozzle 30 onto the inner surface of the metal outercylinder 2. The injected slurry is uniformalized by the brush or roller11 to a uniform thickness and spread in the width direction. The amountof the slurry injected from the nozzle 30 is controlled according to theinjection time and injection pressure of the controller 28.

After the solder material is coated on the inner surface of the metalouter cylinder 2 for a predetermined time, the holding tool 43 isseparated from the electromagnet 35, and the movable table 33 moves tothe original position. When the sensor 34' detects that the movabletable 33 returns to the original position, the cylinder 24 operatesagain to carry the metal outer cylinder to the metal outer cylinderrotating and supporting chuck 25. At this moment, the soldermaterial-coated metal outer cylinder is pushed out by the next metalouter cylinder, and carried by the metal outer cylinder carrying-outguide 38 to the metal outer cylinder recovery box 39.

The above procedure is automatically repeated.

BEST MODE FOR PRACTICING THE INVENTION

Then, the present invention will be described further in detail withreference to the embodiments.

EXAMPLE 1

A corrugated plate, formed by corrugating a 50 μm thick ferrite-typestainless steel flat plate, was supplied on the surface and backsidewith a slurry comprising a powder-formed solder material under 50 μm anda water-soluble binder from a nozzle at positions of 5 mm and 15 mm,respectively, from the end face on the surface, and at positions of 10mm and 20 mm, respectively, from the end face on the backside, spread bya brush to a width of 2 mm and a solder material coating thickness ofless than 50 μm, stacked with a flat plate and wound round to form ametal honeycomb core body. Next, a slurry comprising the powder-formedsolder material and an organic binder was coated on an inner surface ofa 1.5 mm thick metal outer cylinder in a width of 15 mm from a position5 mm apart from the end face of the metal honeycomb core body and dried,and then the above honeycomb core body was pressed into the metal outercylinder. After that, vacuum soldering (heated at 1,200° C. for 20minutes, 10⁻⁵ torr) was performed to prepare a 50 mm diameter, 50 mmlong metal carrier (length of metal honeycomb core body: 40 mm). Thehoneycomb carrier prepared by this method is shown in FIG. 11. In FIG.11, the reference numeral 41 denotes a solder material on the surface ofthe corrugated plate, 42 denotes a solder material on the backside, and1a denotes an exhaust gas inlet side end face. The honeycomb carrier hadan unjoined area of a length of 10% of the length of the metal honeycombcore body from the exhaust gas inlet side end face 1a, and the metalhoneycomb core body was joined to outer cylinder 2 with four joiningstripes 4 perpendicular to the axial direction on the same surface.Further, the average joining interval of the flat plate and thecorrugated plate was about 45 μm.

A catalyst was carried on this metal carrier, and subjected to a heatcycle test (1,000° C.×30 min→cooling×10 min). After the test for 300hours, the metal carrier of the present invention showed no breakage ofthe foil except for a slight cell deformation in the metal honeycombcore body comprising the corrugated plate and the flat plate. Further,to test durability to vibrations, the metal carrier was tested atvibration frequencies of 20 to 500 Hz, an acceleration of 30G, for 20hours. As a result, no defects such as dislocation of the honeycombcore, breakage of the soldered portion, or the like were noted.

EXAMPLE 2

A corrugated plate, formed by corrugating a 50 μm thick ferrite-typestainless steel flat plate, was supplied on the surface and backsidewith a slurry comprising a powder-formed solder material under 50 μm anda water-soluble binder from a nozzle, at the exhaust gas inlet side at aposition of 4 mm from the end face on the surface, and at a position of8 mm from the end face on the backside, and at the exhaust gas outletside at positions of 8 mm and 16 mm on the surface and at positions of 4mm and 12 mm from the end face on the backside, and spread by a brush toa width of 2 mm and a solder material coating thickness of less than 50μm, stacked with a flat plate and wound round to form a metal honeycombcore body. Next, a slurry comprising the powder-formed solder materialand an organic binder was coated on an inner surface of a 1.5 mm thickmetal outer cylinder at the exhaust gas inlet side in a width of 8 mmfrom a position 4 mm apart from the end face, and at the exhaust gasoutlet side in a width of 15 mm from a position 4 mm apart from the endface, and dried, and then the above metal honeycomb core body waspressed into the metal outer cylinder. After that, vacuum soldering(heated at 1,200° C. for 20 minutes, 10⁻⁵ torr) was performed to preparea 50 mm diameter, 50 mm long metal carrier (length of metal honeycombcore body: 40 mm). The honeycomb carrier prepared by this method isshown in FIG. 12. In FIG. 12, the reference numeral 41 denotes a soldermaterial on the surface, 42 denotes a solder material on the backside,and 1a denotes an exhaust gas inlet side end face. The honeycomb carrierhad an unjoined area of a length of 7.5% of the length of the metalhoneycomb core body from the exhaust gas inlet side end face, and themetal honeycomb core body was joined with three joining stripesperpendicular to the axial direction on the same surface. Further, theaverage joining interval of the flat plate and the corrugated plate wasabout 48 μm.

A catalyst was carried on this metal carrier, and subjected to a heatcycle test (1,000° C.×30 min→cooling×10 min). After the test for 300hours, the metal carrier of the present invention showed no breakage ofthe foil except for a slight cell deformation. Further, to testdurability to vibrations, the metal carrier was tested at vibrationfrequencies of 20 to 500 Hz, an acceleration of 30G, for 20 hours. As aresult, no defects such as dislocation of the metal honeycomb core body,breakage of the soldered portion, or the like were noted.

EXAMPLE 3

A corrugated plate 32, formed by corrugating a 50 μm thick ferrite-typestainless steel flat plate 31, was supplied on the surface and backsidewith a slurry comprising a powder-formed solder material under 50 μm anda water-soluble binder from a nozzle at a position of 15 mm from the endface on the surface, and at a position of 25 mm from the end face on thebackside, stacked with a flat plate and wound round to form a metalhoneycomb core body. Next, a slurry comprising the powder-formed soldermaterial and an organic binder was coated on an inner surface of a 1.5mm thick metal outer cylinder 2 on both end faces and in a width of 10 mfrom a position 20 mm apart from both end faces in the axial directionof the metal honeycomb core body, and in a length of 8 mm ateight-divided positions in the peripheral direction. Further, the slurrywas coated at the center of the metal honeycomb core body in a width of15 mm and in a length of 8 mm at eight-divided positions in theperipheral direction. After the slurry was coated intermittently in theaxial and peripheral directions and dried, the above metal honeycombcore body was pressed into the metal outer cylinder 2. After that,vacuum soldering (heated at 1,200° C. for 20 minutes, 10⁻⁵ torr) wasperformed to prepare a metal carrier. Structure of the metal carrierprepared by this method is shown in FIG. 16. In FIG. 16, the referencenumeral 41 denotes a solder material on the surface, 42 denotes a soldermaterial on the backside, and 4 denotes the solder material between themetal outer cylinder and the metal honeycomb core body. A catalyst wascarried on this metal carrier, and subjected to a durability testcombining a heat cycle test with a vibration test (heat cycle test:1,000° C.×12 min→forced cooling×30 min, exhaust gas flow: 10 m³ /min,vibration test: frequencies of 20 to 500 Hz, an acceleration of 30G, asweep time of 5 min (sine)). After the test for 300 hours, the metalcarrier of the present invention showed no breakage of the foil exceptfor a slight cell deformation in the metal honeycomb core bodycomprising the corrugated plate and the flat plate.

EXAMPLE 4

A corrugated plate 32, formed by corrugating a 50 μm thick ferrite-typestainless steel flat plate 31, was supplied on the surface and backsidewith a slurry comprising a powder-formed solder material under 50 μm anda water-soluble binder from a nozzle at positions of 25 mm, 65 mm, and85 mm, respectively, from the end face on the surface of the metalhoneycomb core body, and at positions of 10 mm, 40 mm, and 70 mm,respectively, from the end face on the backside, stacked with a flatplate and wound round to form a metal honeycomb core body. Next, aslurry comprising the powder-formed solder material and an organicbinder was coated on an inner surface of a 1.5 mm thick metal outercylinder 2 in a width of 5 mm in the axial direction on the end face andat positions 15 mm, 30 mm, 45 mm, 60 mm, 75 mm, and 90 mm, respectively,from the end face of the metal honeycomb core body and in a length of 8mm at eight-divided positions in the peripheral direction. After theslurry was coated intermittently in the axial and peripheral directionsand dried, the metal honeycomb core body was pressed into the metalouter cylinder. After that, vacuum soldering (heated at 1,200° C. for 20minutes, 10⁻⁵ torr) was performed to prepare a metal carrier. Thesoldering structure of the metal carrier is shown in FIG. 17. A catalystwas carried on this metal carrier, and subjected to a durability testcombining a heat cycle test with a vibration test (heat cycle test:1,000° C.×12 min→forced cooling×3 min, exhaust gas flow: 10 m³ /min,vibration test: frequencies of 20 to 500 Hz, and acceleration of 30G, asweep time of 6 min (sine)). After the test for 300 hours, the metalcarrier of the present invention showed no breakage of the foil exceptfor a slight cell deformation in the metal honeycomb core bodycomprising the corrugated plate and the flat plate.

COMPARATIVE EXAMPLE 1

A 50 μm thick ferrite-type stainless steel flat plate and a corrugatedplate, formed by corrugating the flat plate, were wound round to form acylindrical metal honeycomb core body, which was inserted into an outercylinder made of a 1.5 mm thick ferrite-type stainless steel, coatedwith a solder material by dipping in a width of 15 mm from the exhaustgas inlet side and outlet side end faces, and subjected to vacuumsoldering (heated at 1,200° C. for 20 minutes, 10⁻⁵ torr) to prepare ametal carrier. The resulting metal carrier is shown in FIG. 13. In theFigure, the a solder material 4 is coated at the same position on thesurface and backside of the corrugated plate. A catalyst was carried onthe metal carrier, and subjected to a heat cycle test (1,000° C.×30min.→cooling×10 min.). As a result, cell deformation and breakage in thefoil on the outer periphery of the metal honeycomb core body were notedafter 83 hours of test. Further, after a vibration test at vibrationfrequencies of 20 to 500 Hz, an acceleration of 30G, for 20 hours,dislocation in the metal honeycomb core body and breakage in the joinedportion were noted.

COMPARATIVE EXAMPLE 2

A corrugated plate, formed by corrugating a 50 μm thick ferrite-typestainless steel flat plate, was stacked with a flat plate and woundround to prepare a honeycomb core. During the step, a 20 μm thick, 2 mmwide amorphous foil solder 41' was supplied at positions of individually5 mm and 15 mm from the end face on the surface, and at positions of 10mm and 20 m from the end face on the back side, and both plates werestacked and wound round to prepare a honeycomb core. Further, a 15 mmwide amorphous foil solder 4 was wound at a position 5 mm apart from theend face on the outer perphery of the metal honeycomb core body, pressedinto a 1.5 mm thick metal outer cylinder, and subjected to vacuumsoldering (heated at 1,200° C. for 20 minutes, 10⁻⁵ torr) to prepare a50 mm diameter, 50 mm long metal carrier (length of metal honeycomb corebody: 40 mm). The metal carrier is shown in FIG. 14. In FIG. 14, thereference numeral 41' denotes a portion soldered with the amorphous foilsolder on the surface of the corrugated plate, and 42' denotes a portionsoldered with the amorphous foil solder on the backside of thecorrugated plate. The metal carrier had an unjoined area of 10% of thelength of the metal honeycomb core body from the end face as in Example1, and the metal honeycomb core body was joined with four joiningstripes perpendicular to the axial direction on the same surface.

A catalyst was carried on this metal carrier, and subjected to a heatcycle test (1,000° C.×30 min.→cooling×10 min). After the test for 300hours, the metal carrier showed slight cell deformation, and cracks werenoted in the portions joined with the amorphous foil solder. Further,after a vibration test at vibration frequencies of 20 to 500 Hz, anacceleration of 30G, for 20 hours, breakage occurred at the portionsoldered with the amorphous foil solder, and a dislocation was noted inthe metal honeycomb core body.

Further, since the amorphous foil solder contains boron, considerableoxidation of the joined portions was noted.

COMPARATIVE EXAMPLE 3

A corrugated plate, formed by corrugating a 50 μm thick ferrite-typestainless steel flat plate, was coated on the surface and backside witha slurry comprising a powder-formed solder material under 50 μm and awater-soluble binder at positions of 5 mm and 15 mm from the end face,stacked with a flat plate and wound round to prepare a metal honeycombcore body. Next, a slurry comprising the powder-formed solder materialand an organic binder was coated on an inner surface of a 1.5 mm thickmetal outer cylinder in a width of 15 mm from a position 5 mm apart fromthe end face and, after drying, the metal honeycomb core body waspressed into the metal outer cylinder. After that, vacuum soldering(heated at 1,200° C. for 20 minutes, 10⁻⁵ torr) was performed to preparea 50 mm diameter, 50 mm long metal carrier (length of metal honeycombcore body: 40 mm). The resulting metal carrier is shown in FIG. 15. Themetal honeycomb core body after vacuum soldering had an unjoined areabetween the flat plate and corrugated plate. Further, the joined portionof the flat plate and corrugated plate has a solder material thicknessof 120 μm. The metal carrier had only half the punching strength ofExample 1 at the solder material portion.

COMPARATIVE EXAMPLE 4

A corrugated plate 32, formed by corrugating a 50 μm thick ferrite-typestainless steel flat plate 31, was stacked with the flat plate and woundround to prepare a metal honeycomb core body, a 20 μm thick, 10 mm widefoil solder was wound round the individual end face of the metalhoneycomb core body, and the metal honeycomb core body was pressed intoa 1.5 mm thick metal outer cylinder 2. Then, a slurry comprising apowdered solder material and a binder was coated by dipping in a widthof 10 mm from the end face of the metal honeycomb core body. After thatthe metal honeycomb core body was subjected to soldering (heated at1,200° C. for 20 minutes, 10⁻⁵ torr) to prepare a metal carrier. Thesoldering structure of the metal carrier is shown in FIG. 18. A catalystwas carried on this metal carrier, and subjected to a durability testcombining a heat cycle test with a vibration test (heat cycle test:1,000° C.×12 min→forced cooling×3 min, exhaust gas flow: 10 m³ /min,vibration test: frequencies of 20 to 500 Hz, an acceleration of 30G, asweep time of 5 min (sine)). After the test for 100 hours, the metalcarrier showed a breakage in about 60% of the periphery, and generationof a telescope.

COMPARATIVE EXAMPLE 5

A corrugated plate 32, formed by corrugating a 50 μm thick ferrite-typestainless steel flat plate 31, was stacked with the flat plate and woundround to prepare a metal honeycomb core body. A slurry comprising apowdered solder material and a binder was coated by dipping in a widthof 10 mm from the end face of the metal honeycomb core body, andsubjected to soldering (heated at 1,200° C. for 20 minutes, 10⁻⁵ torroto prepare a metal honeycomb core body. Then, a 20 μm thick, 10 mm widefoil solder was wound round the center of the metal honeycomb core body,the metal honeycomb core body was pressed into a 1.5 mm thick metalouter cylinder 2, and again subjected to soldering to prepare a metalcarrier. The soldering structure of the metal carrier is shown in FIG.19. A catalyst was carried on this metal carrier, and subjected to adurability test combining a heat cycle test with a vibration test (heatcycle test: 1,000° C.×12 min→forced cooling×3 min, exhaust gas flow: 10m³ /min, vibration test: frequencies of 20 to 500 Hz, an acceleration of30G, a sweep time of 5 min (sine)). After the test for 80 hours, becausethe soldered portion between the metal honeycomb core body and the metalouter cylinder was broken, a dislocation occurred in the metal honeycombcore body in the axial direction of the metal carrier.

UTILIZABILITY IN INDUSTRY

With the use of the honeycomb structure and the production methodthereof according to the present invention, an exhaust gas cleaningmetal carrier for automobiles, autobicycles, and industrial equipment,which is superior in durability, could be achieved.

We claim:
 1. A method for producing an exhaust gas cleaning metalcarrier in the form of a metal honeycomb core body formed by winding astack of a flat plate and a corrugated plate, with the core beinginserted into a metal outer cylinder, said method comprisingconveying acorrugated plate having peaks on each opposed surface thereof through aslurry coating zone; applying to the peaks of corrugations on each ofthe opposed surfaces of the corrugated plate while the corrugated plateis being conveyed through the slurry coating zone a plurality ofparallel rows of spots or stripes of slurry comprising powder-formedsolder material and binder, such that each parallel row on one surfaceis offset with respect to the next adjacent parallel row on the opposedsurface, and while controlling the amount of slurry such that thethickness of the solder material in the to be soldered portions of theflat plate and corrugated plate is 100 μm or less; stacking the slurrycoated corrugated plate and a flat plate; winding the stack to form themetal honeycomb core body; coating a slurry comprising powder-formedsolder material and binder in the form of a plurality of stripes on aninner wall surface of the metal outer cylinder, said stripes beingoffset from an end face of the metal honeycomb core body a distancecorresponding to more than 5% of the length of the metal honeycomb corebody; pressing the metal honeycomb core body into the metal outercylinder; and joining the core body and outer cylinder by soldering theapplied stripes of solder.
 2. The method of claim 1 further comprisingspreading the spots or stripes of slurry applied to the peaks of thecorrugated plate in the longitudinal and cross directions to make thecoating thickness more uniform.
 3. The method of claim 1 furthercomprising forming a plurality of said metal honeycomb core bodies andpressing said plurality of core bodies in the axial direction into themetal outer cylinder.
 4. A method of producing an exhaust gas cleaningcatalyst including at least one metal honeycomb core body inserted inthe axial direction into a metal outer cylinder, comprisingcoating aflowable slurry comprising powder formed solder material and binder inthe form of spots or stripes on the peaks of corrugation of a corrugatedplate; stacking the coated corrugated plate and a flat plate and windingthe resulting stack to form the metal honeycomb core body; applyingstripes of flowable solder material on an inner wall surface of saidmetal outer cylinder; drying the flowable solder material on the innerwall surface; pressing at least one said metal honeycomb core body intosaid metal outer cylinder while the flowable slurry on the peaks ofcorrugation maintains its fluidity; curving the metal outer cylinder toa desired curvature; drying the flowable slurry on the peaks ofcorrugation; and, applying sufficient heat to effect soldering of saidmetal honeycomb core to said metal outer cylinder.
 5. A method ofproducing an exhaust gas cleaning metal carrier including a plurality ofmetal honeycomb core body inserted in the axial direction into a curvedmetal outer cylinder, comprisingcoating a flowable slurry comprisingpowder formed solder material and binder on the peaks of corrugation ofa corrugated plate; stacking the coated corrugated plate and a flatplate and winding the resulting stack to form the metal honeycomb corebody; providing a curved metal outer cylinder; applying stripes offlowable solder material on an inner wall surface of said curved metalouter cylinder; drying the flowable solder material on the inner wallsurface; pressing said plurality of metal honeycomb core body into saidcurved metal outer cylinder while the flowable slurry maintains itsfluidity; curving the metal outer cylinder to a desired curvature;drying the flowable slurry on the peaks of corrugation; and, applyingsufficient heat to effect soldering of said metal honeycomb core to saidcurved metal outer cylinder.
 6. The method of claim 5 which furthercomprises an additional step of further curving the curved metal outercylinder.
 7. The method of any one of claim 1, 4, or 5, wherein thepowder formed solder material has a particle size of 50 μm or less. 8.The method of claim 1 wherein the step of applying spots or stripes ofslurry to the peaks of corrugations further comprises applying saidspots or stripes such that there is a solder-free portion over at least5% of the length of the honeycomb core body from at least one end facethereof.
 9. The method of claim 8 wherein in each row of spots orstripes of slurry applied to peaks of corrugation the spots or stripesare spaced to provide solder-free portions having a length which is morethan 5% of the length of the metal honeycomb core body.
 10. The methodof claim 9 wherein the stripes of solder joining the core body and outercylinder are offset from the solder material in the outermost peripheryof the honeycomb.
 11. The method of claim 4 or claim 5 wherein the stepof coating a flowable slurry in the form of spots or stripes on thepeaks of corrugation comprises coating the slurry in the form of spotsor stripes under conditions such that slurry-free portions having alength of at least 5% of the length of the metal honeycomb core body arepresent from an end face thereof and between the spots or stripes ofslurry.
 12. The method of claim 10 wherein said steps of applyingstripes of flowable solder on an inner wall surface of said metal outercylinder and pressing at least one said metal honeycomb core body intosaid metal outer cylinder cause the dried flowable solder material onthe inner wall surface to be offset from the flowable slurry on thepeaks of corrugation at the periphery of the metal honeycomb core body.